The present invention relates to a new and improved construction of a connection device for a screened or shielded cable.
In its more particular aspects the invention relates to a new and improved construction of radiation tight connection device for a cable containing a screening mesh or meshwork (wire) which is fixed by clamping, wherein an insert or insert member equipped with an insert cone and having a collar formed thereat is inserted substantially axially parallel into a conical bore of a retaining nut or screw cap or the like.
In order to prevent superimposing of signals carried by a line or conductor by signals externally of the line there are frequently used cable screening or shielding devices formed of metal mesh or wires. Such shields or screens are of growing importance due to the increased sensitivity of the employed equipment. In military applications and particularly when working with military hardware, it is additionally necessary to protect the critical lines not only against the usual electromagnetic disturbances, but also against the forces of so-called electro-magnetic pulses (EMP). These pulses are generated, for instance, by nuclear explosions and can exceed intensities of several thousand volts.
In the case of connection devices the transition locations between the screening mesh or wire and stationary parts of the equipment frequently constitute the locations where disturbances arise. During combing out of the screening meshwork or wires at the connection devices frequently there are formed openings which cause electromagnetic untightness or leakiness. Also, soldering operations performed during connection of the screening or shielding meshwork, due to the thermal action, frequently constitute the cause of fracture locations at the screening meshwork.
In U.S. Pat. No. 3,889,046 there is taught to the art a connection device for a shielded or screened cable which, apart from containing other components, contemplates the provision of four flat metal rings equipped with eccentric openings. These metallic rings are pressed by clamping screws against the screening meshwork or wire which is placed over a cone. Due to the offset arranged openings of the metallic rings the meshwork is pressed with different pressures against the cone. Apart from the complicated construction, with this design of connection device there is present an appreciable fracture or rupture danger due to the pronounced loading of fine screening meshworks or wires.
In German Pat. No. 2,343,030 there is taught to the art a releasable connection device for a coaxial cable having solid or air space insulation between the inner conductor and the sheathed outer conductor or line. For purposes of fixing the outer line there is provided a clamping screw, wherein apart from the provision of a retaining nut there is contemplated the use of an insert member or insert having two external threads as well as a supporting sleeve which is attached by being screwed onto the protective jacket. This device which is provided for coaxial cables contains a multiplicity of constructional elements which are superfluous for the connection of shielding meshworks or wires, and therefore is quite expensive.